Silver halide emulsion containing a sulpho substituted disulphide as stabilizer

ABSTRACT

LIGHT-SENSITIVE SILVER HALIDE EMULSIONS ARE PROVIDED WHICH COMPRISE A DISULPHIDE COMPOUND OF THE FORMULA: ((R,A-PHENYL)-S-S-),R,A-BENZENE WHEREIN   A IS A SULPHO GROUP OR A SULPHO GROUP CARRYING SUBSTITUENT, THE SULPHO GROUP BEING IN ACID OR SALT FORM, AND R IS HYDROGEN OR A SUBSTITUENT.   THE EMULSION HAS IMPRIVED STABILITY AND FOGGING CHARACTERISTICS.

the following general formula:

United States Patent Int. oi. G03c 1/34 Claims ABSTRACTOFVTHE DISCLOSURE.

Light-sensitive silver halide emulsions are provided which comprise a disulphide compound of the formula:

wherein:

A is a sulpho group or a sulpho group carrying substituent,

the sulpho group beingin acid or salt form, and R is hydrogen or a substitutent.

The emulsion has improved stability and fogging characteristics.

This invention relates to photographic materials, more particularly" to light-sensitive silver halide emulsions comprising compounds having fog-inhibiting or stabilizing properties.

It is well known that light-sensitive silver halide materials comprising gelatin silver halide emulsion layers are subject to fogging. Fogging in general and chemical fogging in particular may be defined as the formation of a uniform deposit of silver on development which is dependent on a whole series of circumstances and factors namely .on the nature of the emulsions, on their age, on the conditions under which they have been stored, on the development' conditions, etc. For particular development condiwherein: V

pho group being in acid orsalt form, and

R stands for hydrogen or asubstitutent such as alkyl, halogen, alkoxy and sulpho in acid or salt form,

: exert a fog-inhibiting action on light-sensitive photographic emulsions without giving rise to an objectionable desensi- 3,761,277 Patented Sept. 25, 1973 tization thereof, and are particularly suitable to reduce fogformation in photographic colour emulsions comprising colour forming couplers.

The compounds having the structures listed below are representatives of those falling within the scope of the above general formula.

O Na

NaO;S

Na0aSS-SS0s.Na 311:: Hail NaO;S- s-ssoiNa SOaNa I OONH s- Q Q 1.

Compounds 1, 2 and 3 can be prepared according to the method described by H. A. Smith, G. Doughthy and G.

Gorin in J. Org. Chem., 29, (1964), 1484.

Compound 4 was prepared as follows:

7.44 g. (0.03 mole) of 4,4'-dithiodianiline and 16.5 g. (0.09 mole) of o-sulphobenzoic anhydride were boiled for 11 hours in 150 ml. of pyridine. The solution was concentrated by evaporation whereupon the residue was dissolved in water and neutralized with sodium carbonate. The solution was again concentrated by evaporation and the pyridine residues were removed. The residue was recrystallized from ml. of water. Yield: 8 g. (40%). Melting point: 260 C.

The compounds according to the present invention are generally incorporated into the silver halide emulsion layer of the light-sensitive material. The way in which the compounds of use according to the invention are added to the emulsions is not critical and the addition can be made during no matter what step of emulsion preparation, they can be added before or after the emulsion has been optically sensitized, preferably just before coating of the emulsion on a suitable support such as for example paper, glass or film.

Instead of incorporating the compounds of the invention into the emulsion layer they can also be incorporated into another water-permeable colloid layer of the photographic material, e.g. a gelatin antistress layer or intermediate layer, which is in water-permeable relationship with the said emulsion layer.

The compounds of use according to the present invention may be incorporated into any type of light-sensitive material comprising a silver halide emulsion e.g. an X ray or other nonspectrally sensitized emulsion, a silver halide emulsion of use in diffusion transfer processes for the production of silver images, an orthochromatic, panchromatic and infrared-sensitive emulsion etc. They may be incorporated into high speed negative material as well as into rather low speed positive materials. Various silver salts may be used as light-sensitive salt e.g. silver bromide, silver iodide, silver chloride, or mixed silver halides e.g. silver chlorobromide or silver-bromo-iodide.

The antifoggants of use according to the present invention are particularly suitable for use in silver halide ma- .terials intended for colour photography, for example,

materials containing colour-forming couplers which, by reaction with the oxidation product of aromatic primary amino developing agents such as those of the p-phenylene diamine type, form dyestuffs. In these emulsions most of the known antifoggants are unsuccessful to reduce the fog, which is largely due to the presence of the colour coupler, or give rise to a marked decrease in sensitivity. They were also found particularly suitable for use in colour radiographic material containing colour forming coupler compounds e.g. colour radiographic material as described in published Dutch patent application 6912843 and US. patent application Ser. No. 852,246.

The silver halides can be dispersed in the common hydrophilic colloids such as gelatin, casein, zein, polyvinyl alcohol, carboxymethylcellulose, alginic acid, etc. gelatin being, however, favoured.

The amount of compound according to the present invention employed in the light-sensitive silver halide material depends on the particular type of emulsion and the desired effect and can vary within very wide limits. The optimum amount to be added is best determined for each particular type of emulsion by trial. The most suitable concentration of compound according to the present invention is generally comprised between 0.005 millimole and 1 millimole, preferably between 0.01 millimole and 0.25 millimole per mole of silver halide.

The light-sensitive emulsions may be chemically as well as optically sensitized. They may be chemically sensitized by effecting the ripening in the presence of small amounts of sulphur containing compounds such as allyl thiocyanate, allyl thiourea, sodium thiosulphate, etc. The emulsions may also be sensitized by means of reductors for instance tin compounds as described in our British patent specification 789,823 and small amounts of noble metal compounds such as gold, platinum, palladium, iridium, ruthenium and rhodium.

Furthermore, the emulsions may also comprise compounds which sensitize the emulsion by development acceleration for example alkylene oxide polymers. These alkylene oxide polymers may be of various types. Various derivatives of alkylene oxides may be used to sensitize the silver halide emulsions e.g. alkylene oxide condensation products as described among others in US. patent specifications 2,531,832 and 2,533,990 in UK. patent specifications 920,637, 940,051, 945,340 and 991,608 and in Belgian patent specification 648,710. Other compounds that sensitize the emulsion by development acceleration and that are suitable for use in combination with the compounds of use according to the invention are the quaternary ammonium compounds and onium derivatives of amino-N-oxides as described in UK. patent specification 1,121,696.

In conjunction with light-sensitive materials comprising compounds according to the above general formula there may also be used known stabilizers for instance heterocyclic nitrogen containing thioxo compounds such as benzothiazoline-Z-thione and l-phenyl-n -tetrazoline- 5-thione, mercury compounds such as those described in Belgian patent specifications 524,121 and 677,337 and in UK. Pat. Nos. 1,173,609 and 1,194,401 and compounds of the hydroxytriazolo-pyrimidine type (hydroxyazaindolizines) such as 5-methyl-7-hydroxy-s-triazolo[1,5-a] pyrimidine particularly in extreme storage and development circumstances.

Other addenda such as hardening agents, coating aids, plasticizers, colour couplers, developing agents and optical sensitizers can be incorporated into the emulsion in the usual way.

The following examples illustrate the stabilizing or foginhibiting action of the compounds according to the invention.

EXAMPLE 1 A conventional photographic gelatino silver bromoiodide emulsion (4.5 mole percent iodide) comprising per kg. an amount of silver halide equivalent to 50 g. of silver nitrate was divided into four portions. To three of these portions one of the compounds according to the invention was added in a concentration of A; millimole per kg. of emulsion. Then the emulsions were coated on a conventional support and dried.

The values of speed, gradation and fog of the materials formed were determined shortly after preparation and after incubation for 5 days at 57 C. and 34% relative humidity. The values obtained are listed in the table below. The values I and II given for the speed are relative values corresponding with density 0.1 above fog and density 1 above fog respectively; the speed of the fresh comparison material comprising no compound according to the invention is given the value 100.

Development occurred at 20 C. for 5 min. in a developing solution having the following composition:

Water cc 800 p-Monomethylaminophenol sulphate g 1.5 Sodium sulphite (anhydrous) g 50 Hydroquinone g 6 Sodium carbonate (anhydrous) g 32 Potassium bromide g 2 Fater to make 1000 cc.

TABLE Fresh material Incubated material Speed Speed Compound Grada- Gradaadded Fog tion I II Fog tion I 11 None 0.11 1.61 100 100 0 69 1.61 93 103 Compound 1-.- 0.05 1.71 60 73 0.11 1.76 118 111 Compound 2... 0. 07 1. 57 69 71 0.19 1. 53 136 107 Compound 3..- 0.05 1.76 60 73 0.07 1.82 97 10s EXAMPLE 2 To a negative blue-sensitive silver brornoiodide emulsion (5 mole percent of iodide) comprising per kg. g. of gelatin, an amount of silver halide equivalent to 86 g. of silver nitrate, and a yellow forming colour coupler having the formula:

Water ml 900 Sodium hexametaphosphate g 1 Anhydrous sodium sulphate g 4 N,N-diethyl-p-phenylene diamine hydrochloride g 2.7 Anhydrous sodium carbonate g 25 Potassium bromide g 2.2 Sodium carbonate g 0.55

Water to makel litre After treatment for 2 min. at 18-20 C. in an intermediate bath comprising 30 g. of sodium sulphate in 1 litre of water, the material is rinsed for 15 min. with water and treated in a bleach bath of the following composition:

G. Borax 20 Anhydrous potassium bromide 15 Anhydrous sodium bisulphate 4.2 Potassium hexacyanoferrate (III) Water to make 1 litre.

After bleaching, the material is rinsed with water for 5 min. and fixed in an aqueous solution of 200 g. of sodium thiosulphate per litre.

After a final rinsing for 15 min. the material showing a yellow wedge image is dried.

" EXAMPLE 3 To a positive blue-sensitive gelatino silver chlorobromide (28.mole percent of chloride) emulsion comprising per kg. 76 g. of gelatin, an amount of silver halide equivalent to 72 g. of silver nitrate and a yellow forming colour coupler having the formula:

7 E E-niadoomoo Q H CIa aaO are added per kg.: one of the compounds of the invention as listed in the table below in the amounts given, 660 mg. of 5 methyl-7-hydroXy-s-triazolo[1,5-a]pyrimi- .dine as well as common additives such as hardeners and vcoating aids.

, The emulsion is coated on a cellulose triacetate support and then overcoated, with a gelatin antistress layer. After exposure of the material formed, through a grey wedge havinga constant of 0.15 the material is colourprocessed using 2-amino-5-diethylamino-toluene hydrochloride as colour-developing agent.

The results obtained with freshly prepared material and with material that has been stored for 6 days at 57 C. and 34% relative humidity are listed in the following table:

Fresh material Stored material Compound added per kg. of Relative Relative emulsion Fog speed Fog speed None 11 100 0. 18 83 4.5 ml. of a 1% aqueous solution The values given for the speed are relative values corresponding with density 1 above fog; the speed of the fresh material comprising no compound of the invention is given the value 100.

EXAMPLE 4 To a negative green-sensitized silver bromoiodide emulsion (5 mole percent of iodide) comprising per kg. 77 g. of gelatin, an amount of silver halide equivalent to 80 g. of silver nitrate and a magenta forming colour coupler having the following formula:

SO Na (N-ethyl-N-B-methylsulphonylaminoethyl)amino toluene sulphate as colour developing agent.

The results are as follows:

Fog produced after development for Compound added per kg. of emulsion 15 min. 20 min.

Nona 0. 12 0. 5 ml. of a 1% aqueous solution of Compound 3 0. 07 0.09 2.5 ml. of a 1% aqueous solution of Compound 3 0 07 0.09 1.25 ml. of a 1% aqueous solution of Compound 3..- 0 08 0. 12

What we claim is:

1. A light-sensitive silver halide emulsion comprising as an antifogging and stabilizing agent a disulphide compound corresponding to the following general formula:

wherein: p

A stands for a sulpho group or a sulpho group carrying substitutent, the sulpho group being in acid or salt form, and R stands for hydrogen, alkyl, halogen, alkoxy, or a sulpho group in the acid or salt form;

said disulphide compound being present in an amount Sufiicient to inhibit fogging or improve the stability of said emulsion, said amount being from about 0.005 to 1 millimole per mole of silver halide.

2. A photographic silver halide emulsion according to claim 1, wherein said emulsion also comprises a polyoxyalkylene development acceleration.

3. A photographic silver halide emulsion according to claim 1, wherein said disulphide compound is present in a ratio of 0.01 millimole to 0.25 millimole per mole of silver halide.

4. A light-sensitive silver halide emulsion according to claim 1, wherein said antifogging and stabilizing agent is bis(m-sulphophenybdisulphide in acid or salt form.

5. A light-sensitive silver halide emulsion according to claim 1, wherein said antifogging and stabilizing agent is bis(p-sulphophenyl)disulphide in acid or salt form.

6. A light-sensitive silver halide emulsion according to claim 1, wherein said antifogging and stabilizing agent is bis(p-sulpho-o-tolyl)disulphide in acid or salt form.

7. A light-sensitive silver halide emulsion according to claim 1, wherein said antifogging and stabilizing agent is his [p-(o-sulphobenzoylamino)phenyl]disulphide in acid or salt form.

8. A photographic element comprising a support coated with water-permeable colloid layers including at least one light-sensitive silver halide emulsion layer, wherein one of said layers comprises an antifoggant or stabilizer corresponding to the following general formula:

wherein:

A stands for a sulpho group or a sulpho group carrying substitutent, the sulpho group being in acid or salt form, and

R stands for hydrogen, alkyl, halogen, alkoxy, or a sulpho group in the acid or salt form;

said antifoggant or stabilizer being present in an amount suflicient to inhibit fogging or improve the stability of said emulsion, said amount being from about 0.005 to 1 millimole per mole of silver halide.

9. A photographic element according to claim 8, wherein said element also comprises a hydroxytriazolo-pyrimidine stabilizer.

10. A photographic element according to claim 9, wherein said hydroxytriazolopyrimidine is -methyl-7-hydroxy-s-triazolo 1,5-a] pyrimidine.

11. A photopraghic element according to claim 8, wherein said element also comprises a polyoxyalkylene development accelerator.

12. A photographic element according to claim 8, wherein said element comprises one or more light-sensitive silver halide emulsion layers containing a colour coupler, which on colour development by means of an aromatic primary amino colour developing agent forms a dye image.

13. A light-sensitive silver halide emulsion useful in colour photography comprising a colour-forming coupler and as an antifogging and stabilizing agent a disulphide compound corresponding to the following general formula:

wherein:

A stands for a sulpho group or a sulpho group carrying substitutent, the sulpho group being in acid or salt form, and

R stands for hydrogen, alkyl, halogen, alkoxy, or a sulpho group in the acid or salt form;

said disulphide compound being present in an amount sufiicicnt to inhibit fogging or improve the stability of said emulsion, said amount being from about 0.005 to l millimole per mole of silver halide.

14. A light-sensitive silver halide emulsion comprising a hydroxytriazolopyrimidine stabilizer and as an antifogging and stabilizing agent a disulphide compound corresponding to the following general formula:

wherein:

A stands for a sulpho group or a sulpho group carrying substituent, the sulpho group being in acid or salt form, and

R stands for hydrogen, alkyl, halogen, alkoxy, or a sulpho group in the acid or salt form;

said disulphide compound being present in an amount sufficient to inhibit fogging or improve the stability of said emulsion, said amount being from about 0.005 to 1 millimole per mole of silver halide.

15. A light-sensitive emulsion according to claim 14,

wherein said hydroxytriazolopy'rimidine is 5-methyl-7-hydroxy-s-triazolo[ 1,5-a] pyrimidine.

References Cited UNITED STATES PATENTS 1,962,133 6/1934' Brooker et al 96-109 2,440,110 4/ 1948 Mueller 96109 2,440,206 4/1948 Mueller 96-109 3,397,986 8/1968 Millikan ct al. 96-109 NORMAN G. TORCHIN, Primary Examiner W. H. LOUIE, 111., Assistant Examiner us. or. X.R. 96-69, 74, 100 

